In order to establish his arguments, Strawson made a distinction between three aspects of sentence, and correspondingly three aspects of expression, which are as follows.

1. A sentence
2. A use of a sentence
3. An utterance of a sentence

Correspondingly;

1. An expression
2. A use of an expression
3. An utterance of an expression

In considering the sentence "The present king of France is bald", he states that it is a pre-supposition which can't be judged as either true or false. It is because France is not under monarchy, and there is no such king found in France. So truth or falsity does not arise. Further, he enunciates that every sentence is not a case of "assertion". The sentence "The present king of France is bald" does not assert anything - an object or an individual. The reason is it is just a sentence, but not a true or false sentence. 'Truth' or 'falsity' arises when we "use" a sentence in the language system. Thus, a sentence itself cannot be judged as either true or false. To put it differently, a bare sentence can't be treated as either true or false.

Similarly, he evinces that 'expression' as such does not have any "referent". It denotes the reference when we 'use' it in our language. Thus, to use an expression means to refer to an individual/object or to describe about an individual/object.